calipso

The CALIPSO tag on WindowsForum.com covers discussions about the Common Architecture Label IPv6 Security Option, a kernel-level networking feature. Recent content focuses on CVE-2025-38181, a null-pointer dereference vulnerability in CALIPSO option handling that was fixed with defensive checks in calipso_req_setattr() and calipso_req_delattr(). Microsoft's Security Response Center has attested that Azure Linux includes the affected open-source code, though this attestation is product-scoped and does not guarantee other Microsoft products are unaffected. The tag is relevant for security researchers, IT administrators, and developers tracking Linux kernel vulnerabilities, particularly those affecting Azure Linux and potentially other Microsoft products. Topics include kernel patching, vulnerability assessment, and cross-product risk analysis.